Offshore crane heave compensation control system and method using visual ranging

An heave compensation control system using visual ranging for an offshore crane, comprising:

• a detecting device,
• a controlling device and
• an actuating device,
• the heave compensation control system is configured to achieve heave motion compensation automatically while the offshore crane is loading down and up cargo to a supply vessel, by adding a movement with the same direction and same amplitude to the supply vessel;
• wherein:
• the detecting device is configured to detect a three-dimensional position information of the supply vessel using a visual ranging method, and transmit the detected parameters of three-dimensional position information to the controlling device,
• the controlling device is configured to control the actuating device to achieve heave compensation movement automatically while the offshore crane is loading down and up the cargo to the supply vessel, by adding the movement with the same direction and amplitude to the supply vessel;
• the offshore crane is positioned on a fixed offshore platform;
• the three-dimensional position information means displacement, velocity and acceleration information in various directions which is referred to a rectangular coordinate system including the heave direction and the three-dimensional attitude of the supply vessel;
• and
• the movement with the same amplitude and same direction means the supply vessel moves along with a periodic motion of the ocean waves with the same amplitude and same direction.